The present invention relates to a process for producing a hollow composite-fiber body from wound fibers, running in a plurality of directions and embedded in a curable or fusible plastics composition, having at least one lug integrated without any interruption into the fiber-composite and protruding from the hollow fiber-composite body. In this process, a plastics-impregnated and circumferentially continuous wound jacket is produced on a wound body, the lug is freed by cuts and set up, an the finished shaped blank of the hollow fiber-composite body is cured.
In the case of the above generic process, fibers impregnated with curable plastic are wound crosswise around an elongated, shaping winding body. To form lugs, tabs, flanges or the like (referred to hereinafter throughout as lugs) protruding from the later formed hollow fiber-composite body, after winding the fibers on the hollow body in the region of the lug to be formed, the lug is freed by cuts and exposed in a shaping manner. Finally, the part is cured.
However, since winding is performed only with a single fiber, this process is very time-intensive and consequently cost-intensive. Furthermore, during the setting-up of the lugs, the differing radii of the fiber layers previously wound with the fiber cause bulges in their curvatures or folds of the individual fiber layers, which prevent or eliminate an intimate contact of the individual layers.
The object of the invention is therefore to provide an improved process to produce a hollow fiber-composite body with lugs without any folds in the root region of the lugs.
This and other objects are achieved by the present invention which provides a process for producing a hollow composite-fiber body from wound fibers, running in a plurality of directions and embedded in a curable or fusible plastics composition, having at least one lug integrated without any interruption into the fiber-composite and protruding from the hollow fiber-composite body. This process includes forming a plastics-impregnated and circumferentially continuously wound jacket by winding one layer over the other on a shaping core a plurality of layers of at least one prepreg web having web-bound, crossing groups of parallel-running fibers. The lug is shaped and secured by a support corresponding to a set-up lug shape and which protrudes during winding from the shaping core. Immediately after the running on of the prepreg web onto the shaping core or the wound body which is forming, into the prepreg web for each separate layer a lug free cut is made that corresponds to the position and contour of the respective lug. The lug free cut is set up separately and pressed into place without any folds onto the support or onto the prepreg layers already laid there for the lug with each revolution of the shaping core and for each lug to produce a finished shaped blank. The finished shaped blank is then cured.
By cutting into the prepreg web, or a fiber lay which is preimpregnated and/or provided with fusible fibers, in a way corresponding to the lug shape and the lug position immediately before running onto the wound body, each lug free cut of each prepreg winding can, individually and already during winding, be set up and pressed into place without any folds layer by layer at its corresponding support arranged on the wound body, or lug support, or at the previous lug free cut. Since these processing steps are performed within one working step and with prepreg webs, the fabrication time is also reduced in an advantageous way in comparison with the filament winding technique.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.